Operating system for locking pins for sliding undercarriages

ABSTRACT

A operating system for slider locking pins includes an air compressor connected to an air supply tank. An air pressure protection valve is connected to the air tank to protect the brake system of the trailer. A flipper valve is connected to the air pressure protection valve and provides selective fluid communication between the air tank and a plurality of locking pin driver assemblies. Each locking pin driver assembly is adapted to move a locking pin to a disengaged position when in fluid communication with the air tank while being adapted to move the locking pin to the engaged position when not in fluid communication with the air tank. Each driver assembly is configured to substantially provide protection to each of its elements from adverse weather conditions and articles thrown up from the road. In one embodiment, the driver assembly includes a fixed bracket attached to the frame of the sliding undercarriage. A traveling bracket is connected to a locking pin. A return spring is disposed about locking pin and disposed to create a constant force driving the locking pin to the engaged position. An expandable air bladder is disposed between the fixed bracket and the traveling bracket. The expandable bladder is in fluid communication with the flipper valve such that when the flipper valve is manipulated to provide fluid communication between the air bladder and the air tank, the air bladder expands driving the locking pin to the disengaged position.

RELATED APPLICATIONS

This application is a continuation of Ser. No. 09/111,497, filed Jul. 8,1998, now U.S. Pat. No. 6,213,489.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to a locking pin operating system for securing asliding undercarriage to the suspension frame of a semitrailer. Moreparticularly, the present invention relates to the driver assembliesthat drive the locking pins from an engaged position to a disengagedposition and then back again to the engaged position. Specifically, thepresent invention relates to a locking pin operating system thatincludes a single manually-operated valve that selectively directspressurized air to expandable chambers wherein expansion of the chambersdrives locking pins to disengaged positions while release of thepressurized air from the chambers allows springs to drive the lockingpins to the engaged positions.

2. Background Information

In the United States, a tractor/semitrailer combination has been one ofthe most common modes of transportation of goods since World War II. Thetractor/semitrailer combination includes a tractor having an engine,transmission, steerable front axle with wheels, and one or more reardrive axles and wheels. The tractor is attached to the semitrailerthrough a fifth wheel which is located over the tractor's rear driveaxle. The semitrailer is unpowered and rides on one or more axles havinga plurality of wheels. The semitrailer also includes a braking systemand a suspension that are operated and adjusted from the tractor.

As the use of tractor/semitrailers grew over the years and their sizeincreased, federal and state laws were passed that limit the weight peraxle for tractors and semitrailers. It thus became desirable to be ableto shift the load of the trailer to more evenly distribute its weightover the various axles. In order to redistribute the weight, a slidingundercarriage was developed that allows the relative position of thesemitrailer's load to be adjusted with respect to the axles of thesemitrailer. A sliding undercarriage typically includes a pair of sliderrails having a linear array of locking pin holes disposed along theirlength. The slider rails slidably engage the frame of the suspension forthe semitrailer and are held thereto by various devices. One device thatholds the relative position of the slider rails with respect to thesuspension frame is a locking pin. A sliding undercarriage typicallyincludes two or four locking pins disposed about the corners of thesuspension frame.

When the locking pins are engaged between the slider rails and theframe, the slider rails and load carrying portion of the semitrailercannot be adjusted with respect to the wheels and suspension frame. Thelocking pins must be retracted to a disengaged position to allow theload carrying portion of the semitrailer to be adjusted along thesuspension frame.

Both non-manual and manual systems are known in the art for moving thelocking pins from an engaged position to a disengaged position and backto the engaged position. One manual system includes a handle connectedto a torsion bar. A plurality of links connect each locking pin to thetorsion bar. When adjustment of the semitrailer is required, the driverlocks the brakes on both the tractor and semitrailer. The driver thenclimbs out of the tractor, walks to the sliding undercarriage, and pullsor lifts the manually operated locking pin release handle. This handleis typically positioned adjacent the wheels carried by the suspensionframe. The pulling or lifting of the handle transmits a force throughthe links which overcomes the spring-loaded locking pins causing them tomove to a disengaged position. The manual system typically includesmeans for holding all of the pins in the disengaged position while thedriver returns to the tractor to reposition the sliding undercarriage.To reposition the undercarriage, the driver releases the brakes on thetractor while leaving the brakes on the semitrailer's slidingundercarriage engaged. The tractor is then driven forward or backward toslide the semitrailer relative to the sliding undercarriage. The driverthen reapplies the tractor brakes and leaves the tractor to return tothe sliding undercarriage to release the handle allowing the pins toreturn to the engaged position. Unfortunately, the spring-loaded lockingpins are not usually perfectly aligned with the locking pin holes suchthat they all may not slide directly back into the engaged position.When this occurs, the driver returns to the tractor, releases thetractor brakes, and moves the semitrailer or rocks the semitrailer untilthe spring-loaded pins align with the locking pin holes and return tothe engaged position. The driver must then reapply the brakes and walkaround the semitrailer to visually verify that all pins are in theengaged position. The manually operated pin retraction systems, such asthe one described above, often become impossible to operate due todamage or corrosion of the linkages and contamination with dirt or icefrom exposure to the elements. The locking pins themselves can alsobecome stuck in the locking pin holes when the semitrailer is parked onan incline or positioned with a twist in the frame. A common occurrenceis that the driver will use a hammer to pound the locking pins from theengaged position to the disengaged position. Such hammering oftendamages the pins causing future operation of the manual system to bedifficult.

In view of these problems with the manual system, non-manual systemsusing compressed air delivered from the braking system of thesemitrailer were developed. One example of such a system can be found inU.S. Pat. No. 5,314,201. Still other improvements to that system may befound in U.S. Pat. Nos. 5,465,990, 5,564,727, and 5,620,195. Thesesystems utilize compressed air delivered from the tractor to operate thebraking and suspension systems of the semitrailer to move the lockingpins between engaged and disengaged positions. These systems employpiston/cylinder combinations connected to the locking pins wherebyselective delivery of pressurized air to the piston/cylinder causes thelocking pin to move. Although these non-manual systems providesignificant improvements over the manual system discussed above,improved driver assemblies and operating system configurations are stilldesired in the art.

For instance, the air cylinders used in the prior art to drive thelocking pins between the engaged and disengaged positions are relativelyexposed to the elements and unprotected from debris that may be thrownup from the road by the rear wheels of the tractor. It is thus desiredin the art to provide a driver assembly that protects its moving partsfrom the elements to prevent or at least hinder the negative effects ofwater, salt, snow, and ice on the driver assembly. Another undesirableaspect of the driver assemblies of the prior art is their relative size.It is desirable to provide a driver assembly that is as compact aspossible so that it may be fit onto various types of trailers withoutmodification of the trailer. One difficulty with providing a compactdriver assembly is that the locking pins are relatively long compared tothe portion of the locking pin that actually locks the semitrailer bodyto the sliding undercarriage frame. Furthermore, the air cylindersdisclosed in the prior art are relatively long with their pistonsextending therefrom to further increase their length. It is also desiredin the art to provide a compact, weather resistant driver assembly for alocking pin system that provides an accommodating or flexible connectionbetween the locking pin and the driver assembly to accommodate movementof the locking pin with respect to the frame.

SUMMARY OF THE INVENTION

In view of the foregoing, the primary objective of the present inventionis to provide an operating system for slider locking pins.

Another objective of the present invention is to provide an operatingsystem for slider locking pins that utilizes air pressure alreadyavailable on the tractor-trailer.

Still another objective of the present invention is to provide anoperating system for slider locking pins that provides a safetymechanism that protects the braking system of the trailer.

Yet another objective of the present invention is to provide anoperating system for slider locking pins that may be installed ontoexisting trailer frames without substantial modification of the trailerframes.

Another objective of the present invention is to provide an operatingsystem for slider locking pins that includes driver assemblies that aresubstantially compact.

A further objective of the present invention is to provide an operatingsystem for slider locking pins that is designed to withstand adverseweather conditions such as water, ice, mud, and the like.

Yet a further objective of the present invention is to provide anoperating system for slider locking pins that is strong enough towithstand various shock forces that may occur on the road such asimpacts from debris and the like.

Still a further objective of the present invention is to provide anoperating system for slider locking pins utilizing an expandable airbladder that is substantially impervious to weather and providesreliable operation through repeated use.

Another objective of the present invention is to provide an operatingsystem for slider locking pins utilizing minimal moving parts.

A further objective of the present invention is to provide an operatingsystem for slider locking pins utilizing a return spring that isprotected from the elements.

Another objective of the present invention is to provide an operatingsystem for slider locking pins that provides continuous pressure to thelocking pins holding them in position while in use.

Another objective of the present invention is to provide an operatingsystem for slider locking pins utilizing a piston cylinder assembly thatencloses the return spring.

Another objective of the present invention is to provide an operatingsystem for slider locking pins utilizing the locking pin as a moveablecylinder in cooperation with a fixed piston.

A further objective of the present invention is to provide an operatingsystem for slider locking pins utilizing a service chamber and linkagemechanism that moves a locking pin between the engaged and disengagedpositions.

Another objective of the present invention is to provide an operatingsystem for slider locking pins that is of simple construction, whichachieves the stated objectives in a simple, effective, and inexpensivemanner, and which solves the problems and which satisfies the needsexisting in the art.

These and other objectives and advantages are obtained by the operatingsystem of the present invention, the general nature of which may bestated as including a source of air pressure; a main supply line influid communication with the source of air pressure; a first valve influid communication with the main supply line, the first valve movablebetween open and closed positions; at least two locking pins; a returnspring associated with each of the locking pins, each of the returnsprings continuously forcing one of the locking pins into an engagedposition; a locking pin driver assembly connected to each of the lockingpins; and each of the locking pin driver assemblies including anexpandable bladder in fluid communication with the valve, each of theexpandable bladders overcoming one of the return springs when the firstvalve is in the open position moving one of the locking pins to adisengaged position.

Other objectives and advantages are obtained by the operating system ofthe present invention, the general nature of which may be stated asincluding a source of air pressure; a main supply line in fluidcommunication with the source of air pressure; a first valve in fluidcommunication with the main supply line, the first valve movable betweenopen and closed positions; at least two locking pins; a return springassociated with each of the locking pins, each of the return springscontinuously forcing one of the locking pins into an engaged position; alocking pin driver assembly connected to each of the locking pins; eachof the driver pin assemblies comprising: a hollow fixed bracket; acylinder carried by the bracket; a piston engaging the cylinder, thepiston connected to the locking pin; and the return spring beingdisposed within the cylinder, the return spring engaging the piston; thepiston disposed within the cylinder and the hollow fixed bracket.

Still other objectives and advantages are obtained by the operatingsystem of the present invention, the general nature of which may bestated as including a source of air pressure; a main supply line influid communication with the source of air pressure; a first valve influid communication with the main supply line, the first valve movablebetween open and closed positions; at least two locking pins; a returnspring associated with each of the locking pins, each of the returnsprings continuously forcing one of the locking pins into an engagedposition; a locking pin driver assembly connected to each of the lockingpins, each of the locking pin driver assemblies comprising: a pistonhaving a shaft; the shaft of the piston adapted to be connected to thesuspension frame; the locking pin defining a cylinder; the piston beingdisposed in the cylinder; and a base attached to the locking pin to forma chamber between the base, cylinder, and the piston; the chamber influid communication with the first valve; the shaft of the pistonextending through the base of the cylinder.

Yet other objectives and advantages are obtained by the operating systemof the present invention, the general nature of which may be stated asincluding a source of air pressure; a main supply line in fluidcommunication with the source of air pressure; a first valve in fluidcommunication with the main supply line, the first valve movable betweenopen and closed positions; at least two looking pins; a return springassociated with each of the locking pins, each of the return springscontinuously forcing one of the locking pins into an engaged position; alocking pin driver assembly connected to each of the locking pins, eachof the driver assemblies comprising: a service chamber in fluidcommunication with the first valve; the service chamber having an outputshaft; and lever means connecting the output shaft to the locking pinfor moving the locking pin to the disengaged position when the shaft isextended from the service chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the invention, illustrative of the bestmodes in which the Applicant contemplated applying the principles of theinvention, are set forth in the following description and are shown inthe drawings and are particularly and distinctly pointed out and setforth in the appended claims.

FIG. 1 is a side elevational view of the rear portion of a slidingundercarriage attached to a trailer frame.

FIG. 2 is a top plan view of the trailer frame incorporating theoperating system of the present invention with the semitrailer removed,the slider rails depicted in dashed lines.

FIG. 3 is a detailed view of the area appearing in the dashed circledepicted in FIG. 2.

FIG. 4 is a sectional view taken substantially along line 4—4 of FIG. 3showing the pin in the engaged position.

FIG. 5 is a sectional view substantially similar to FIG. 4 depicting thepin in a disengaged position.

FIG. 6 is a top plan view of a portion of the trailer frame showing onelocking pin engaged with another locking pin disengaged.

FIG. 7 is a view substantially similar to FIG. 6 showing both lockingpins engaged.

FIG. 8 is a sectional view substantially similar to FIG. 4 depicting afirst alternative embodiment of the present invention with the lockingpin in the engaged position.

FIG. 9 is a sectional view substantially similar to FIG. 8 showing thefirst alternative embodiment in the disengaged position.

FIG. 10 is a sectional view substantially similar to FIG. 4 depicting asecond alternative embodiment of the present invention with the lockingpin in the engaged position.

FIG. 11 is a sectional view substantially similar to FIG. 10 depictingthe locking pin in the disengaged position.

FIG. 12 is a plan view of a portion of the trailer frame depicted withthe semitrailer removed for clarity depicting a third alternativeembodiment of the present invention with the locking pin engaged.

FIG. 13 is a plan view substantially similar to FIG. 12 depicting thelocking pin in the disengaged position.

FIG. 14 is an elevational view of the third alternative embodiment ofthe present invention.

Similar numbers refer to similar elements throughout the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The operating system of the present invention is used in conjunctionwith the semitrailer 10 depicted in the drawings. As may be seen in FIG.1, semitrailer 10 includes a sliding undercarriage, indicated generallyby the numeral 12, that is adjustably mounted on a trailer frame,indicated generally by the numeral 14. Sliding undercarriage 12 includesa pair of substantially parallel, spaced slider rails or body rails 16.Each rail 16 is attached by appropriate means to the body 18 ofsemitrailer 10 such that adjustment of the position rails 16 adjusts theposition of body 18. Frame 14 includes at least a pair of side rails 20connected by a plurality of cross bars 22. As may be seen in FIG. 1,frame 14 may also include a frame bracket 24 that extends downwardlyfrom side rail 20. Beams 26 pivotally extend forwardly and rearwardlyfrom frame bracket 24 to at least partially support a suspension airspring 28. The locations of the wheels of semitrailer 10 are depicted inFIG. 1 by the dashed lines labeled with the numeral 30.

Frame 14 also includes at least two safety clips or hold down clamps 32attached to each rail 20 that slidably engage slider rail 16. Eachsafety clip 32 may be attached to frame 14 by any appropriate means suchas a weld or a nut and bolt combination 34. As may be seen for examplein FIG. 4, safety clip 32 includes a hook portion 36, that substantiallysurrounds and slidably engages a flange 38 of slider rail 16. It maythus be understood that semitrailer 10 is retained on frame 14 laterallythrough the engagement between safety clips 32 and flange 38.Semitrailer 10 is retained longitudinally with respect to frame 14 by atleast a plurality of locking pins 40 that are selectively disposed inlocking pin holes 42 disposed in slider rails 16. Holes 42 are disbursedalong the entire length of the slider rail 16 and are typically spacedat equal intervals. Engagement between locking pins 40 and slider rail16 also vertically retains semitrailer 10 with respect to frame 14.

As discussed in the Background of the Invention section of thisspecification, it is desirable for semitrailer 10 to be adjustable withrespect to frame 14. As such, body 18 of semitrailer 10 is supported byslider rails 16 which, in turn, are slidably disposed on frame 14 whenlocking pins 40 are disengaged. Slider rails 16 slidably engage bearingsor sections of glide material 44 attached to the upper surface 46 ofside rails 20 of frame 14. Bearings 44 may be attached to upper surface46 of rails 20 by any of the numerous appropriate means known in the artbut may be preferably attached by a plurality of screws 48 as depictedin the drawings.

In accordance with one of the main objectives of the present invention,an improved operating system for slider locking pins 40 is provided andis indicated generally by the numeral 50 in the accompanying drawings.Operating system 50 allows each of locking pins 40 to be retracted to adisengaged position by manipulating a single valve. Operating system 50employs a minimum of elements and moving parts to ensure itsreliability. Operating system 50 obtains pressurized air from the airtank 52 that is carried by frame 14 to provide pressurized air to thebraking system of the tractor trailer. Air tank 52 obtains a supply ofcompressed air from the compressor 54 disposed on the tractor 56. Aplurality of detachable pigtail supply lines 58 selectively attach airtank 52 to compressor 54. Operating system 50 includes a brakeprotection valve 60 connected to air tank 52. Brake protection valve 60is configured to sense air pressure in air tank 52 and close when theair pressure in air tank 52 drops below a predetermined level that isthe minimum for operating the braking system. The suspension operatingsystem 62 branches out of one side of brake protection valve 60 whilelocking pin operating system 50 branches from the other side of brakeprotection valve 60.

A main supply line 64 provides fluid communication between brakeprotection valve 60 and a flipper valve 66 that is disposed betweenwheels 30 and carried by one of side rails 20 of frame 14. Main supplyline 64 may be fabricated from any of a variety of known materials butit is preferred that supply line 64 is fabricated from a relativelyflexible material. It is preferred that flipper valve 66 be disposedbeneath rail 20 as depicted in the drawings as it is a shelteredlocation. The exact location of flipper valve 66 is not, however,critical to the present invention. Main supply line 64 provides aconstant source of pressurized air to flipper valve 66 when brakeprotection valve 60 senses adequate air pressure in air tank 52. Flippervalve 66 is used to selectively direct pressurized air from main supplyline 64 to each of locking pins 40 causing them to move to thedisengaged position. It is to be understood that operation of flippervalve 66 directs the pressurized air to all of locking pins 40simultaneously.

Flipper valve 66 includes an outlet line 68 that provides fluidcommunication between a T-joint 70 and flipper valve 66. A pair ofsecondary supply lines 72 provide fluid communication between T-joint 70and a second pair of T-joints 74. A pair of primary supply lines 76provide fluid communication between T-joint 74 and locking pin driverassemblies 78 that cause locking pins 40 to engage and disengage sliderrails 16.

It is generally desirable to fabricate line 68 and lines 72 from agenerally flexible material. Furthermore, primary supply lines 76 arefabricated from a generally flexible material for a reason more clearlydescribed below with reference to FIGS. 6 and 7. Each of lines 64, 68,72, and 76 may be supported from frame 14 in a manner to provideprotection from the elements and debris that may be thrown up from theroad by the wheels of the tractor 56 or semitrailer 10. Similarly,flipper valve 66 is also disposed in a sheltered location. Flipper valve66 is also provided with a cover 80 that substantially surrounds valvehandle 82 in a manner that prevents exposure to the elements andaccidental operation of flipper valve 66. To provide additionalprotection, a face plate 84 may be provided that must be detached fromcover 80 prior to operating valve 66.

Another objective of the present invention is to provide operatingsystem 50 with reliable locking pin driver assemblies 78 that utilize anexpandable air bladder to move locking pins 40. A view of one embodimentof locking pin driver assembly 78 meeting this objective is depicted inFIGS. 3-5. Assembly 78 includes a fixed bracket 90 attached to an innerwall 92 of rail 20. Bracket 90 may be attached by any of a variety ofattachment means known in the art such as the bolts 94 depicted in thefigures or by appropriate welds. A traveling bracket 96 is attached tothe shaft 98 of locking pin 40 by appropriate means such as the bolt orscrew 100 depicted in the drawings. A return spring 102 is disposedabout shaft 98 to create an outwardly directed force on locking pin 40.Spring 102 is seated against inner wall 92 and a shoulder 104 of lockingpin 40 such that locking pin 40 is constantly urged outwardly into alocking pin hole 42 to the engaged position. When locking pin 40 isdisposed in a locking pin hole 42 as shown in FIGS. 3 and 4, it is saidto be in the engaged position. Spring 102 urges locking pin 40 outwardlyuntil traveling bracket 96 engages inner wall 92 to counteract the forceof spring 102. As can be perhaps best seen in FIGS. 4 and 5, rail 20 issubstantially hollow thus forming a protective covering around most oflocking pin 40 and return spring 102.

The driving member of assembly 78 that moves locking pin 40 from theengaged position to the disengaged position depicted in FIG. 5 is anexpandable air bladder in the form of an air spring 106. Air spring 106is disposed between fixed bracket 90 and traveling bracket 96. Asdepicted in the drawings, air spring 106 may be connected to fixedbracket 90 by appropriate means such as a screw or bolt 108. As is alsodepicted in the drawings, air spring 106 includes a fixture that extendsthrough traveling bracket 96 to fluidly connect with primary supply line76. A reliable connection may be formed by a lock nut 110.

With specific reference to FIGS. 3 and 4, fixed bracket 90 includes apair of spaced apart feet 120 that are connected by a U-shaped portion122. Traveling bracket 96 includes two opposed ends 124 connected by apair of opposed sides 126. Shaft 98 of locking pin 40 is attached to oneof ends 124 while the other of ends 124 is attached to one end of airspring 106. The other end of air spring 106 is attached to U-shapedportion 122 of fixed bracket 90. Fixed bracket 90 and traveling bracket96 are also disposed such that U-shaped portion 122 is disposed betweensides 126. There is, however, accommodating space between U-shapedportion 122 and traveling bracket 96.

Traveling bracket 96 is only slidably and loosely supported on fixedbracket 90 such that it moves with locking pin 40 and may accommodateskewed movement by locking pin 40. The use of air spring 106 allows afluid-tight connection to be maintained while accommodating skewedrelative movement between locking pin 40 and fixed bracket 90. Whenpressurized air is supplied to air spring 106, air spring 106 creates anexpansive force between traveling bracket 96 is urged away from rail 20such that locking pin 40 is pulled inwardly toward the disengagedposition. Air spring 106 is sized sufficiently and the air pressure issufficient to provide enough force to overcome spring 102 and anyfriction occurring between pin 40 and slider rail 16. Traveling bracket96, fixed bracket 90, and air spring 106 are sized such that travelingbracket 96 engages fixed bracket 90 when locking pin 40 has reached thedisengaged position depicted in FIG. 5 to counteract the expansion ofair spring 106. In an alternative embodiment, air spring 106 is adaptedto ccasc expansion when locking pin 40 is in the disengaged position.

Locking pin 40 remains in the disengaged position until the supply ofpressurized air delivered by air tank 52 through flipper valve 66 is cutoff. When the supply of pressurized air is cut off, return spring 102expands and drives locking pin 40 back toward the engaged positiondepicted in FIG. 4. A frequent occurrence with semitrailers employingslider rails 16 is that slider rails 16 are not perfectly aligned withrails 20 when return spring 102 forces locking pin 40 back toward theengaged position. This occurrence is depicted in FIG. 6 where it isshown that locking pin 40 on one side has returned to the engagedposition while locking pin 40 at the other side has lodged against theinner surface of slider rail 16. FIG. 6 also depicts the necessity offabricating primary supply line 76 from a relatively flexible material.When traveling bracket 96 moves away from rail 20, primary supply line76 must flex as indicated at numeral 112 to accommodate the movement oftraveling bracket 96. When locking pin 40 is jammed, as depicted in FIG.6, the user of operating system 50 returns to tractor 56 and creates arocking motion between semitrailer 10 and frame 14. This rocking motionis typically sufficient to realign locking pin 40 with locking pin hole42 allowing return spring 102 to force locking pin 40 back to theengaged position as shown in FIG. 7.

In view of the foregoing, it may be understood that locking pin driverassembly 78 provides a reliable mechanism for driving locking pin 40between the engaged and disengaged positions. Driver assembly 78 issubstantially protected from the elements and potential damage fromdebris thrown up from the road, The use of air spring 106 provides acompact mechanism that generates forces large enough to overcomefriction between pin 40 and slider 16 and other jamming forces such asice or rust.

Operating system 50 does not require air pressure to maintain pins 40 inthe engaged position. Thus, pins 40 return to the engaged position upona failure of air tank 52 or compressor 54.

A second alternative embodiment of the locking pin driver assembly ofthe present invention is depicted in FIGS. 8 and 9 and is indicatedgenerally by the numeral 278. Driver assembly 278 includes a fixedbracket 290 that extends inwardly from inner wall 92 of frame rail 20.Fixed bracket 290 is hollow and includes an annular flange 292. Fixedbracket 290 may be attached to rail 20 by any of a variety of suitablemeans known in the art. In the second embodiment of the presentinvention, the traveling member is in the form of a piston 296 that isslidably received in a cylinder 298 that is substantially rigidlyattached to a base 304 which is, in turn, carried by flange 292 of fixedbracket 290. A seal 300 is seated in a groove in piston 296 to provide afluid tight connection between piston 296 and cylinder 298. A secondseal 302 is provided in base 304 of cylinder 298 to form a sealedchamber 306 between piston 296 and base 304. Chamber 306 is in fluidcommunication with primary supply line 76 such that chamber 306 may befilled with pressurized air when flipper valve 66 is opened. A returnspring 308 is disposed in cylinder 298 between a grooved cylinder endcap 310 and piston 296. Thus, it may be understood that piston 296 isdisposed between chamber 306 and spring 308.

Piston 296 includes a shaft 312 that may include a threaded bore 314.Piston 296 may be attached to locking pin 40 by any of a variety ofappropriate means. In the embodiment of the invention depicted in FIGS.8 and 9, piston 296 is attached to locking pin 40 by the connection of afirst pin 320 to a second pin 322. First pin 320 is threaded intothreaded bore 314 of piston 296 and carries a spherical bushing 324 atthe end projected from piston 296. Second pin 322 passes through andthreadably engages at least one of a pair of arms 326 projectinginwardly from locking pin 40. Second pin 322 is further disposed throughspherical bushing 324 such that piston 296 is attached to locking pin 40in an adjustable and accommodating manner. Bushing 324 allows lockingpin 40 to move with respect to piston 296 without creating undesirabletorsion forces in piston 296. Both pins 320 and 322 as well as bushing324 are disposed within fixed bracket 290 and are thus providedprotection. In addition to the protection provided by hollow fixedbracket 290, cylinder 298 substantially protects spring 308 and piston296 from the elements.

The second embodiment of the pin driver assembly 278 is operated bysupplying pressurized air to chamber 306 causing piston 296 to move intocylinder 298. As piston 296 moves inwardly, locking pin 40 is movedtoward the disengaged position. When piston 296 is fully inserted intocylinder 298, locking pin 40 has reached the disengaged positiondepicted in FIG. 9. At this time, spring 308 has also been fullycompressed. When the pressure is released from primary supply line 76,return spring 308 expands forcing piston 296 and pin 40 back toward theengaged position depicted in FIG. 8. It may thus be understood thatdriver assembly 278 provides reliable operation while protecting itselements from the weather and outside forces.

A third embodiment of the driver assembly of the present invention isdepicted in FIGS. 10 and 11 and is indicated generally by the numeral378. Driver assembly 378 includes a piston 396 slidably disposed in acylinder 398. Piston 396 includes a shaft 412 that is connected toprimary supply line 76. Shaft 412 is supported at its projected end by asupport sleeve 414 that is attached to a frame member 416 that may becarried by rail 20 of frame 14. As in the previously describedembodiment, a spherical bushing 424 is employed between support sleeve414 and shaft 412 to accommodate movement of locking pin 40 with respectto frame 14. Shaft 412 is attached to support sleeve 414 by a threadedpin 426 that is received in a threaded bore 428. Pin 426 carriesspherical bushing 424. Pin 426 may be attached to support sleeve 414 bya bolt 430 that extends entirely through sleeve 414 and threadablyengages a nut 432. Bolt 430 may also be used to attach sleeve 414 toframe 14.

Shaft 412 is protected from the elements by a protection sleeve 434 thatis collapsible and expandable. Sleeve 434 extends between primary supplyline 76 and base 404 of cylinder 398. A first seal 400 is providedbetween piston 396 and cylinder 398 and a second seal 402 is providedbetween shaft 412 and base 404 to create a fluid tight chamber 406between base 404 and piston 396. It may be understood that sleeve 434protects outside surface of shaft 412 and thus helps to maintain goodcontact between shaft 412 and second seal 402.

In the third embodiment of the present invention, cylinder 398 isintegrally formed in pin 40 such that cylinder 398 and base 404 movebetween the engaged position and disengaged position when the airpressure supplied by primary supply line 76 is activated anddeactivated. A return spring 408 is disposed within cylinder 398 and isdisposed to urge piston 396 away from locking pin 40. As such, piston396 and shaft 412 remain substantially fixed during the operation ofdriver assembly 378.

Shaft 412 includes an air supply passageway 436 that provides fluidcommunication between chamber 406 and primary supply line 76. When pin40 is in the engaged position, spring 408 is in the expanded positionand chamber 406 is at its minimum volume. When flipper valve 66 isopened, pressurized air is supplied to chamber 406 causing base 404 tomove inwardly along shaft 412. As such, cylinder 398 and thus pin 40 aremoved inwardly towards the disengaged position causing spring 408 tocollapse. When this occurs, sleeve 434 collapses to accommodate themovement. Spring 408 is collapsed until pin 40 reaches the disengagedposition as depicted in FIG. 11.

When the supply of pressurized air is cut off, spring 408 urges cylinder398 and thus locking pin 40 back towards the engaged position pullingbase 404 and sleeve 434 along with it. Substantially all of the elementsof driver assembly 378 are protected from the weather and that areliable driver assembly 378 is provided.

A fourth embodiment of the driver assembly of the present invention isindicated generally by the numeral 478 in FIGS. 12-14. Driver assembly478 of the fourth embodiment includes a service chamber 480 that is influid communication with primary supply line 76. Although somewhatlarger in size than a piston-cylinder assembly, a service chamber 480may be configured to provide significantly more force than a smallpiston-cylinder assembly. Service chamber 480 includes an expandablechamber/spring arrangement (not shown) that is configured to force anoutput shaft 482 outwardly from service chamber 480 when pressurized airis supplied to service chamber 480 by primary supply line 76. Shaft 482is pivotally attached to a first bar 484. First lever bar 484 is rigidlyattached to a second lever bar 486 by a rod 488. Rod 488 is pivotallycarried by a pair of brackets 490 that are, in turn, carried by frame20. Locking pin 40 is pivotally attached to second lever bar 486 byappropriate means such as a second pin 492. A return spring 494surrounds a portion of locking pin 40 and is disposed between inner wall92 and a shoulder 496.

Locking pin 40 may be retracted to the disengaged position by activatingservice chamber 480 by supplying it with pressurized air. Such a supplycauses shaft 482 to move outwardly causing first and second lever bars484, 486 to pivot about the axis of rod 488. As may be seen in FIG. 13,this motion causes locking pin 40 to move inwardly to the disengagedposition to compress return spring 494. When the supply of pressurizedair is released, return spring 494 urges locking pin 40 back to theengaged position and resets service chamber 480. Of course, other leverarrangements may also be used to transfer the motion created by servicechamber 480 to locking pin 40. For instance, a longer lever arm may beused to create more force at locking pin 40. However, a longer lever armwill require a longer movement of shaft 482 to fully retract locking pin40. In another embodiment, a straight lever bar may be used with asingle pivot.

It may thus be understood that the fourth embodiment of the driverassembly 478 provides a reliable mechanism for driving locking pin 40between the engaged and disengaged positions. Driver assembly 478 alsoprotects its elements from the weather as the working elements areenclosed by the service chamber 480 or the frame 20 of the semitrailer10.

Accordingly, the improved operating system for slider locking pins issimplified, provides an effective, safe, inexpensive, and efficientdevice which achieves all the enumerated objectives, provides foreliminating difficulties encountered with prior devices, and solvesproblems and obtains new results in the art.

In the foregoing description, certain terms have been used for brevity,clearness, and understanding; but no unnecessary limitations are to beimplied therefrom beyond the requirement of the prior art, because suchterms are used for descriptive purposes and are intended to be broadlyconstrued.

Moreover, the description and illustration of the invention is by way ofexample, and the scope of the invention is not limited to the exactdetails shown or described.

Having now described the features, discoveries, and principles of theinvention, the manner in which the operating system for slider lockingpins is constructed and used, the characteristics of the construction,and the advantageous new and useful results obtained; the new and usefulstructures, devices, elements, arrangements, parts, and combinations areset forth in the appended claims.

What is claimed is:
 1. A semitrailer locking pin operating systemadapted to be used with a trailer having a pair of rails having lockingholes that are selectively slidably carried by a suspension frame, thesystem comprising: a source of air pressure; a main supply line in fluidcommunication with said source of air pressure; a valve in fluidcommunication with said main supply line, said valve movable betweenopen and closed positions; at least two locking pins; a return springassociated with each of said locking pins, each of said return springscontinuously forcing one of said locking pins into an engaged position;a locking pin driver assembly connected to each of said locking pins ata connection, said locking pin driver assembly actuated by said valve,wherein each of said locking pin driver assemblies include an expandablebladder in fluid communication with said valve, each of said expandablebladders overcoming one of said return springs when said valve is insaid open position moving one of said locking pins to a disengagedposition; and a protective covering substantially enclosing said returnspring for preventing debris from inhibiting the operation of saidsemitrailer locking pin operating system.
 2. A system according to claim1 wherein said source of air pressure includes an air compressor and anair tank in fluid communication with said air compressor.
 3. A systemaccording to claim 2 further comprising an air pressure protection valveconnected to said air tank and a main supply line connected to said airpressure protection valve and said valve.
 4. A system according to claim1 wherein said driver assembly comprises: a fixed bracket adapted to beconnected to the suspension frame of the semitrailer; a travelingbracket attached to said locking pin; said expandable air bladderdisposed between said traveling bracket and said fixed bracket.
 5. Asystem according to claim 4 further comprising at least a primary supplyline providing fluid communication between said expandable air bladderand said valve, said primary supply line being flexible.
 6. A systemaccording to claim 5 wherein said fixed bracket includes: a U-shapedportion disposed between a pair of feet, said feet adapted to beconnected to the suspension frame; said traveling bracket including twoopposed ends connected by a pair of opposed sides; one of said endsattached to said locking pin; said expandable bladder disposed betweensaid U-shaped portion of said fixed bracket and the other of said endsof said traveling bracket.
 7. The system according to claim 6 whereinsaid protective covering includes a second protective portion comprisingsaid fixed and said traveling brackets substantially enclosing saidvalve and said locking pin driver assembly.
 8. A system according toclaim 6 wherein said U-shaped portion of said fixed bracket is disposedbetween said sides of said traveling bracket.
 9. A system according toclaim 8 wherein said return spring is disposed around said locking pin.10. A system according to claim 9 wherein said locking pin defines ashoulder, said return spring engaging said shoulder and adapted toengage the suspension frame of the semitrailer.
 11. The system accordingto claim 1 wherein said protective covering includes a first protectiveportion comprising a side rail substantially enclosing said returnspring.
 12. A semitrailer locking pin operating system adapted to beused with a trailer having a pair of rails having locking holes that areselectively slidably carried by a suspension frame, the systemcomprising: a source of air pressure; a main supply line in fluidcommunication with said source of air pressure; a valve in fluidcommunication with said main supply line, said valve movable betweenopen and closed positions; at least two locking pins; a return springassociated with each of said locking pins, each of said return springscontinuously forcing one of said locking pins into an engaged position;a locking pin driver assembly connected to each of said locking pins ata connection, said locking pin driver assembly actuated by said valve;and a protective covering substantially enclosing said return spring forpreventing debris from inhibiting the operation of said semitrailerlocking pin operating system.
 13. The system according to claim 12wherein each of said locking pin driver assemblies have a piston and ashaft with the piston mounted on said shaft, said locking pin formedwith a cylinder therein whereby at least a portion of the piston isdisposed within the cylinder.
 14. A system according to claim 13 whereinsaid shaft of said piston is adapted to be connected to the suspensionframe.
 15. A system according to claim 12 further comprising a baseattached to said locking pin to form a chamber between said base,cylinder, and said piston, said chamber being in fluid communicationwith first valve; said shaft of said piston extending through said baseof said cylinder.
 16. A system according to claim 13 wherein said shaftof said piston is adapted to be connected to the suspension frame in amanner that accommodates skewed movement of said locking pin withrespect to the frame.
 17. A system according to claim 16 furthercomprising: a pin attached to said shaft; a spherical bushing carried bysaid pin; a sleeve adapted to extend between the suspension frame andsaid spherical bushing; and a connector extending through said sphericalbushing and said sleeve.
 18. A system according to claim 17 furthercomprising an expandable and collapsible protection sleeve surroundingat least a portion of said shaft.
 19. The system according to claim 18wherein said protective assembly includes said cylinder and saidprotection sleeve.
 20. A system according to claim 13 wherein said shaftdefines an air supply passageway that partially provides fluidcommunication between said valve and said chamber.
 21. A systemaccording to claim 13 wherein said return spring is disposed within saidcylinder in said locking pin.